MOSCOW — The German people, and the whole world alongside them, are celebrating a landmark date in history, the 20th anniversary of the fall of the Berlin Wall. Not many events remain in the collective memory as a watershed that divides two distinct periods. The dismantling of the Berlin Wall — that stark, concrete symbol of a world divided into hostile camps — is such a defining moment.

The fall of the Berlin Wall brought hope and opportunity to people everywhere, and provided the 1980s with a truly jubilant finale. That is something to think about as this decade draws to a close — and as the chance for humanity to take another momentous leap forward appears to be slipping away.

The road to the end of the Cold War was certainly not easy, or universally welcomed at the time, but it is for just this reason that its lessons remain relevant. In the 1980s, the world was at a historic crossroads. The East-West arms race had created an explosive situation. Nuclear deterrents could have failed at any moment. We were heading for disaster, while stifling creativity and development.